3x00 Compression Ratios

[BigRed95]

I have a 95 3100. Would swapping to a complete 2000+ 3x00 top-end change my compression ratio. And would I need custom pushrods. Surely someone out there has done it before. I have a t3/t04 turbo and I would like to lower my compression a bit to allow for more boost to put the turbo into better efficiency. I could always use thicker head gaskets, but then I'd have to possibly machine the lower intake to match which I don't want to do.

[THe_DeTAiL3R]

Brian P. put a newer top end on his older 3100, IIRC he said the pushrods were the same size. He's be the one to talk to.

[dbtk2]

The compression ratio should not be changed at all by switching heads. I think the only good way for you to lower your compression would be to change the pistons. But, your compression is only 9.4:1 anyways, which is not bad for boost. I was considering using thinner gaskets with my topend swap to get higher compression along with my boost. I ended up not doing it because I was worried about my valves smaking the pistons with my cam and 1.6 rockers, but from what I've been told now, that wouldn't have even been a problem.

 

Shawn

[Brian P]

9.6:1, which is still within range for turboing. You can reuse your old pushrods provided you don't put in a reground custom cam.

[BigRed95]

9.6:1, which is still within range for turboing. You can reuse your old pushrods provided you don't put in a reground custom cam.

 

Thanks guys, that pretty much sums up that question for me!

[Canada]

The big port 3x00s have a compression ratio of 9.5:1.

 

Id rather have a healthy compression ratio and moderate boost, than high boost, low compression. Lag is a bitch.